Dispensed prescriptions for quetiapine and other second-generation antipsychotics in Canada from 2005 to 2012: a descriptive study

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Abstract
Background The use of antipsychotic drugs, particularly quetiapine, has increased at an unprecedented rate in the last decade, primarily in relation to nonpsychotic indications. This increased use is concerning because of the high rates of metabolic and extrapyramidal side effects and inadequate monitoring of these complications. The purpose of this study was to measure the use of quetiapine and other second-generation antipsychotics by primary care physicians and psychiatrists and the most common diagnoses associated with quetiapine recommendations. Methods We analyzed data on antipsychotic use from the IMS Brogan Canadian CompuScript Database and the Canadian Disease and Treatment Index, with a focus on quetiapine. We looked at the number of dispensed prescriptions for second-generation antipsychotics written by primary care physicians and psychiatrists and the diagnoses associated with recommendations for quetiapine from 2005 to 2012. Results Between 2005 and 2012, there was a 300% increase in dispensed prescriptions for quetiapine ordered by family physicians: from 1.04 million in 2005 to 4.17 million in 2012. In comparison, dispensed prescriptions from family physicians for risperidone increased 37.4%: from 1.39 million in 2005 to 1.91 million in 2012; those for olanzapine increased 37.1%, from 0.97 million in 2005 to 1.33 million in 2012. Dispensed prescriptions for quetiapine ordered by psychiatrists increased 141.6%: from 0.87 million in 2005 to 2.11 million in 2012. The top 4 diagnoses associated with quetiapine in 2012 were mood disorders, psychotic disorders, anxiety disorders and sleep disturbances. A 10-fold increase in quetiapine recommendations for sleep disturbances was seen over the study period, with almost all coming from family physicians. Interpretation These findings indicate a preferential increase in the use of quetiapine over other antipsychotic drugs and show that most of the increased use is a result of off-label prescribing by family physicians.

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